package DynamicProgramming;

import java.util.LinkedList;
import java.util.Queue;
import java.util.Vector;

public class FordFulkerson {
  static final int INF = 987654321;
  // edges
  static int V;
  static int[][] capacity, flow;

  public static void main(String[] args) {
    System.out.println("V : 6");
    V = 6;
    capacity = new int[V][V];

    capacity[0][1] = 12;
    capacity[0][3] = 13;
    capacity[1][2] = 10;
    capacity[2][3] = 13;
    capacity[2][4] = 3;
    capacity[2][5] = 15;
    capacity[3][2] = 7;
    capacity[3][4] = 15;
    capacity[4][5] = 17;

    System.out.println("Max capacity in networkFlow : " + networkFlow(0, 5));
  }

  private static int networkFlow(int source, int sink) {
    flow = new int[V][V];
    int totalFlow = 0;
    while (true) {
      Vector<Integer> parent = new Vector<>(V);
      for (int i = 0; i < V; i++) parent.add(-1);
      Queue<Integer> q = new LinkedList<>();
      parent.set(source, source);
      q.add(source);
      while (!q.isEmpty() && parent.get(sink) == -1) {
        int here = q.peek();
        q.poll();
        for (int there = 0; there < V; ++there)
          if (capacity[here][there] - flow[here][there] > 0 && parent.get(there) == -1) {
            q.add(there);
            parent.set(there, here);
          }
      }
      if (parent.get(sink) == -1) break;

      int amount = INF;
      String printer = "path : ";
      StringBuilder sb = new StringBuilder();
      for (int p = sink; p != source; p = parent.get(p)) {
        amount = Math.min(capacity[parent.get(p)][p] - flow[parent.get(p)][p], amount);
        sb.append(p + "-");
      }
      sb.append(source);
      for (int p = sink; p != source; p = parent.get(p)) {
        flow[parent.get(p)][p] += amount;
        flow[p][parent.get(p)] -= amount;
      }
      totalFlow += amount;
      printer += sb.reverse() + " / max flow : " + totalFlow;
      System.out.println(printer);
    }

    return totalFlow;
  }
}
